Shinpei Wada

ABSTRACT Mycobacterium montefiorense , a nontuberculous mycobacterium, is a causative agent of mycobacteriosis in aquatic animals, its type strain M. montefiorense ATCC BAA-256 being isolated from a moray eel. In this study, we report the complete ATCC BAA-256 genome sequence with a 5,693,452-bp-containing circular chromosome, 65.2% GC content, and 5,407 coding sequences.

Mycobacterium chelonae is a nontuberculous mycobacterium that causes infections in various animals, including humans. In this study, we report the draft genome sequence of M. chelonae subsp. bovis strain NJB1701, which was isolated from a Baikal seal (Pusa sibirica) in captivity in Japan.

Mycobacterium marinum is a slow-growing, photochromogenic nontuberculous mycobacterium, which can cause mycobacteriosis in various animals, including humans. Several cases of fish mycobacteriosis have been reported to date. Mycobacterium marinum has also been isolated from aquatic environmental sources such as water, sand, biofilms, and plants in the natural environments. Hence, we hypothesized that a wide variety of sources could be involved in the transmission of M. marinum. In this study, we tested this hypothesis by isolating M. marinum from various sources such as fish, invertebrates, seagrass, periphytons, biofilms, sand, and/or water in two aquaria in Japan and conducting a phylogenetic analysis based on single-nucleotide polymorphisms (SNPs) using whole-genome sequences of the isolated strains. The analysis revealed that the strains from animal and environmental sources belonged to the same clusters. This molecular-based study epidemiologically confirmed that various sources, including fish, invertebrates, and environmental sources, could be involved in transmission of M. marinum in a closed-rearing environment. This is the first report where M. marinum was isolated from different sources, and various transmission routes were confirmed in actual cases, which provided essential information to improve the epidemiology of M. marinum.

INTRODUCTION: Mycobacterium montefiorense is one of the causes of non-tuberculous mycobacterial infections in moray eels and salamanders. Although M. montefiorense infection could be a threat to salamanders, little information is available regarding this pathogen and associated infection. This study aimed to provide fundamental information regarding M. montefiorense and its infection in salamanders. METHODS: Nine M. montefiorense strains isolated from three species of salamanders, namely, Japanese black salamander (Hynobius nigrescens), Hakuba salamander (H. hidamontanus), and Tohoku hynobiid salamander (H. lichenatus), between 2010 and 2018, were characterized based on phenotypic and genetic examination. We also pathologically observed salamanders infected with the M. montefiorense strains, including Hakuba salamanders and Tohoku hynobiid salamanders. RESULTS: The microbiological and chemical characteristics of the M. montefiorense salamander and an eel strain (reference strain) matched. Susceptibility testing for antimicrobials suggested that clarithromycin may be effective. Regarding disinfectants, phtharal, peracetic acid, glutaral, sodium hypochlorite, and benzalkonium chloride may be effective. Phylogenetic analyses revealed that the strains isolated from salamanders in 2014 and 2018 were genetically closely related, which could indicate an outbreak. The main gross findings in infected salamanders include skin ulcerative lesions or nodules in the enlarged liver. Microscopically, multifocal to coalescent granulomatous lesions composed of massive macrophages containing numerous acid-fast bacilli were prominently observed in the liver. CONCLUSION: This study contributes to our understanding of the genetic diversity and phenotypic characteristics of M. montefiorense, as well as the pathology of the infection.

Paracoccidioidomycosis ceti (PCM-C) is a zoonotic mycosis characterized by chronic granulomatous keloidal dermatitis in cetaceans that has been reported worldwide. The causative agents of PCM-C are unculturable Paracoccidioides brasiliensis var. ceti and Paracoccidioides spp., which are genetically identical to one of the causative agents of paracoccidioidomycosis: P. brasiliensis sensu stricto. The definitive diagnosis of PCM-C is based on clinical symptoms and the detection of yeast-like cells during pathological examinations; molecular diagnosis is not essential. However, analyses at the molecular level are important to distinguish PCM-C from other fungal infections showing similar clinical signs. Researchers have been following a suspected case of PCM-C in a Pacific white-sided dolphin (Lagenorhynchus obliquidens) by performing cytology, histopathology, and molecular biology experiments since 2015. Finally, we confirmed it as the fourth Japanese PCM-C case based on the partial sequence of 43-kDa glycoprotein antigen gene (gp43) with 99.4% identity to that from P. brasiliensis sensu stricto from a biopsied sample in October 2019. Then, we applied a loop-mediated isothermal amplification (LAMP) for P. brasiliensis. The simple LAMP targeting for fungal DNA and human clinical materials failed to amplify bands, but a combination of polymerase chain reaction (PCR) and LAMP (PCR-LAMP) could amplify species-specific ladder-like bands identical to P. brasiliensis.